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18.2: Human-Dominated Landscapes

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    In every country on Earth, significant portions of unprotected lands still harbor some of their original biota. Consider, for example, remote regions that are considered “wilderness” by governments and the general public. Most of these areas are inhabited by low-density human societies that practice a traditional way of life. With relatively little outside influence from modern technology, these traditional peoples are often dependent on—and thus highly concerned with—the health of their environment. More importantly, traditional peoples have been an integral part of their environments for thousands of years. The present mixture and relative densities of wildlife in these “wildernesses” thus reflect the historical activities (e.g. fishing, hunting, fire management, land clearing, and planting of useful plant crops) of the people living in those areas (Roberts et al., 2017). These activities do not degrade the environment if human population densities remain low and natural resources are harvested sustainably. To regulate these activities, most traditional societies have an established system of rights to natural resources, known as customary laws, which an increasing number of governments recognize. Conservation biologists should follow this example: rather than being considered a threat to the “pristine” environments in which they live, traditional peoples should be seen as important partners in conservation efforts because protecting their lifestyles also ensures the protection of biodiversity.

    Urban Areas

    People who live in rural areas and sell natural resources that they extract from healthy ecosystems also play an important role in conservation by engaging in sustainable natural resource management. Consider all the unprotected estuaries and marine areas that support commercial fisheries for a moment. When fisheries are managed in a sustainable way, not only does this benefit the people that depend on these commercially important species, but other native species can also thrive.

    People living in urban centers can also contribute to conservation efforts by raising environmental awareness among fellow citizens, participating in activism, lobbying, and fundraising activities, and generating knowledge through citizen science projects. They can also help reduce the multiple pressures that their cities exert on the surrounding environment. Among the most exciting recent developments have been the development and installation of green infrastructure, such as urban forests, green roofs, urban wetlands, permeable sidewalks, urban farms, and rain gardens (Figure 18.2.1). Not only does green infrastructure save money by reducing energy consumption and pollution clean-up costs, it also reduces overall maintenance (Odefey et al., 2012) and improves overall well-being (Demuzere et al., 2014). Consequently, green infrastructure is increasingly being integrated in urban planning across the world, including North America (EPA, 2018), Europe (Natural England, 2009), Asia (e.g. Kennedy et al., 2016), and in South Africa (Culwick et al., 2016).

    Figure 18.2.1 Green infrastructure enables people living in urban centres to reduce their pressure on natural ecosystems and live more comfortable lives. (Top) A green wall to provide cooling and air purification in Madrid, Spain. Photograph by Jean-Pierre Dalbéra,, CC BY 2.0. (Bottom) A constructed wetland in Harbin, China, built to provide flood control, a wildlife refuge, and a nature experience. Photograph by Richard Primack, CC BY 4.0.

    Many urbanites are also eager to work with government agencies and conservation NGOs to make their cities more biodiversity friendly by restoring urban waterways and wetlands, and replanting abandoned industrial sites and other damaged urban areas with native vegetation that can support pollinators, birds, and other wildlife. Such efforts foster neighborhood pride, create a sense of community, and provide a sense of satisfaction to people who like to be close to nature. These restored areas, and other urban green spaces, can also serve to highlight the links between human well-being and nature, which may make those city dwellers who remain on the side-lines of conservation more receptive to the more challenging aspects of conservation, such as prescribed fire and invasive species management (Gaertner et al., 2016). Establishing and maintaining areas to protect biodiversity where people live and work, termed reconciliation ecology (Rosenzweig, 2003), will increase in importance as urban centers continue to expand over the next decades (Seto et al., 2011). Reconciliation ecology can improve biodiversity by providing habitat stepping stones between protected areas.

    The Monarch Butterfly, Danaus plexippus, is an example of a specialist species in decline (Figure 18.2.2) that can be helped by reconciliation ecology efforts. The north American populations migrate great distances from summer to winter ranges and rely specifically on milkweed, Asclepias spp., for reproduction. Caterpillars eat and develop on milkweed and toxins in the plant provide protection for the developing butterfly. Multiple generations are produced during one breading season and require milkweed and nectar sources along the migratory route. Factors causing the decline of Monarch populations in North American are grassland conversion to agriculture, herbicide use, drought, logging in the winter range, and urban development (U.S. Fish and Wildlife Service, 2020, Monarch (Danaus plexippus) Species Status Assessment Report). Planting native milkweed species and pesticide-free nectar sources in rural and urban areas can improve habitat for migrating monarchs.

    Monarch Butterfly on Swamp MilkweedCaterpillar on milkweed in CaliforniaMonarch butterflies overwintering in Pacific Grove, California
    Figure 18.2.2: Top: Monarch butterfly (Danaus pexippus) populations rely on Milkweed for reproduction. Two important North American populations migrate great distances between their winter and summer habitat. (Top: Caterpillar on milkweed. Photo by Ashley Spratt, USFWS Pacific Southwest Region from Sacramento, US, Public Domain via Widimedia Commons, Middle: Adult monarch on milkweed. Photo by Jim Hudgins, USFWS Midwest, Public Domain via Wikimedia Commons, Bottom: Overwintering monarchs on the central California coast. Agunther, CC BY 3.0, via Wikimedia Commons) Graph: Thanksgiving counts showing the number of western North American monarch butterflies observed at overwintering sites (green bars). Blue line shows the number of sites monitored (survey effort) for a given year. (U.S. Fish and Wildlife Service. 2020. Monarch (Danaus plexippus) Species Status Assessment Report., Data from The Xerces Society for Invertebrate Conservation 2020, entire)

    Lessening impacts of agriculture

    Habitat loss from agricultural expansion is one of the biggest current challenges to biodiversity conservation in many parts of the world (Balmford et al., 2012; Laurance et al. 2013; Maxwell et al., 2016). At the root of this problem is the need to supply food and other resources to a growing human population. Exacerbating the situation, much of the Earth's arable land has already been degraded to such a degree that it cannot sustain viable food production anymore (Drechsel et al., 2001). Most of these losses are not due to natural factors, but to poor land management practices, such as overgrazing, continual plowing of fields, and heavy use of fertilizers. These practices release nitrogen, carbon, and oxygen into the atmosphere and compromise the soil’s ability to hold water, leading to erosion, soil salinization, desertification, and even climate change (Vågen et al., 2005). This not only lead to collapsing ecosystem services, but also increased competition for space as even more land must be converted for agriculture, and to accommodate people and their activities. Such land conflicts are only going to become worse with climate change (Zabel et al., 2014).

    In light of the seemingly irreconcilable conflict between agriculture and conservation, some conservation biologists have suggested that the only way in which we can secure a future for biodiversity is through a land sparing approach, in which agricultural investments are focused on intensifying practices on land already dedicated to farming and no more. One of the main drawbacks of such a high-yield approach is that the impact of intensive agricultural practices degrades natural ecosystems even far from the immediate area, for example through nutrient and pesticide pollution. For that reason, others support a land sharing approach that promotes biodiversity-friendly agricultural practices, even if that means agricultural lands continue to expand. One of the main drawbacks of this land-sharing approach is that it still alters ecosystem composition, which would threaten species that need large territories and habitats, in addition to leading to more human-wildlife conflict.

    While the land-sparing versus land-sharing frameworks make for good intellectual debate, the reality is that both are undesirable scenarios when carried out as opposite extremes. There is no denying that agriculture is important, and critical for food security. But because there is a finite amount of land available for food production, we have no choice but to develop methods that will allow greater yields on existing agricultural lands without depleting the soil or damaging more ecosystems. In other words, we need to adopt a hybrid approach where some lands are dedicated to large protected areas where human activities are restricted, some lands are dedicated to wildlife-friendly agro-ecosystems, and some lands are used for intensive food production (Fischer et al., 2014; Law et al., 2017). Traditional farming systems offer many strategies showing how natural ecosystem services can be used to improve yields, including the use of biocontrol and crop diversification to keep pests and diseases at bay, and planting of nitrogen-fixing legumes to improve soil fertility. This is in stark contrast to intensive modern agricultural practices dedicated to single crop specialization; these impoverished ecosystems cannot maintain themselves but rather rely on continuous use of fertilizers and pesticides to remain productive.

    Biodiversity-friendly farming practices can also produce economic benefits; and so, many government programs are now promoting sustainable agricultural intensification.

    With the increased realization that biodiversity-friendly farming practices can also produce economic benefits, many government programs have begun to promote and subsidize the adoption of sustainable agricultural intensification (see also Pretty et al., 2011; Garnett et al., 2013). Also known as conservation agriculture, this farming approach blends traditional agricultural practices with improved and locally adapted crops, as well as integrated crop and pest management strategies (Figure 18.2.3) to boost yields on existing farmland while creating cost and labor savings; it may even reduce the amount of land under cultivation (Stevenson et al., 2013). Some of these strategies include minimal tilling, crop rotation, intercropping, and terracing (to prevent agricultural runoff which, in turn, prevents erosion). Soil nutrient levels are enhanced through fertilizer microdosing, and by planting legumes, encouraging decomposition by termites, and using crop residues as mulch before composting it directly into the soil. Crop yields are further improved by maintaining windbreaks such as riparian buffer zones, which have the added benefit of enhancing the diversity of seed dispersers, biocontrol agents, and pollinators. It is important to remember that conservation agriculture is a departure from both traditional and intensive monocrop farming techniques. Adequately training farmers in best practices and new techniques is therefore crucial to program success (Gatare et al., 2013).

    Figure 18.2.3 A vegetable farm maintained by a local community living adjacent to Gorongosa National Park, Mozambique. The farm is maintained following several conservation agriculture principles. For example, to conserve water, the ground is covered in mulch obtained from a nearby grassy field, while a drip irrigation system was installed by park staff and a local women’s association. To further strengthen local development and collaboration, part of the crop is also sold at the tourist restaurant inside the park. Photograph by Iñaki Abella Gutiérrez/Bio+, CC BY. 4.0.

    To take advantage of the multiple benefits to be gained from integrated, biodiversity-friendly farming techniques, entire industries have started adopting such practices. Among the most prominent are cacao and coffee, where many growers now produce their crops under native shade trees (Box 18.2.1). While Africa has had a long history of shade-grown cacao and coffee production, recent decades have seen many farmers transitioning towards intensive farming in full sun, which allows for easier mechanisation. But crops grown in full sun are generally also of lower quality and more susceptible to pest outbreaks (Kellerman et al., 2008; Bisseleua et al., 2009; Tscharntke et al., 2011). In contrast, shade-grown cacao and coffee benefits both the farmers and biodiversity: a study from Ethiopia found that shade coffee farms had over double the number of bird species in comparison with nearby forest sites (Buechley et al., 2015). Shade farming could also be a strategy for farmers trying to cope with increasing temperatures due to climate change (Blaser et al., 2018). Considering the large global markets for cacao and coffee, reverting to traditional growing methods here would have a large positive impact on the environment simply due to the economy of scale.

    Box 14.3 Preserving Biodiversity Through Shaded Agroforestry

    Hervé D. Bisseleua

    World Agroforestry Centre (ICRAF), Nairobi, Kenya.

    Chocolate is one of the most universal treats in the world, but could your sweet tooth be increasing biodiversity loss? The chocolate tree (Theobroma cacao) is traditionally grown in areas with dense and diverse canopies of shade trees, home to an abundant variety of plants and animals (Figure 14.B). The chocolate industry is strongly dependent on small-scale agriculture, but also highly vulnerable to pest and disease outbreaks, and climate change. These production challenges combined with increasing global demand for chocolate has increased economic and social pressures to achieve higher yields within a shorter timeframe. Higher yields could be achieved through reduced shade tree management and increased use of chemical pesticides and fertiliser. But these techniques lead to deforestation, biodiversity loss, and loss of ecosystem functioning. Higher yield techniques in the short term are also not sustainable over the long term: work in Cameroon and elsewhere showed that the promotion of high-yielding hybrid cacao varieties under direct full sun have contributed to more frequent outbreaks of pests and diseases (Kellerman et al., 2008; Bisseleua et al., 2009; Tscharntke et al., 2011).

    To achieve more sustainable cacao production, and to benefit from ecosystem services, such as enhanced biological control of pests and diseases, and increased soil fertility, West Africa’s cacao farmers are now gradually returning to agroforestry practices that embrace increased shade tree diversity. Farmers adopting these techniques are already reaping benefits. For instance, in Ghana and Cameroon, cacao yields from shaded cacao agroforestry systems are 12–23% higher compared to full sun systems (Bisseleua et al., 2009; Asare and Raebild, 2016). In eastern Côte d’Ivoire, the use of leguminous trees as shade in rehabilitated cacao plantations is also reported to increase the survival rate and yield of cacao trees (Smith Dumont et al., 2014). Cacao grown in shade may produce for 60–100 years, whereas production may only last for 20 years without shade (Obiri et al., 2007). In addition to environmental services, diversified shade trees may also provide additional income opportunities, such as timber and firewood production, medicine, local spices, and fruit, from native shade trees such as the njangsang tree (Ricinodendron heudelotii) and bush mango (Irvingia gabonensis) (Smith Dumont et al., 2014). Importantly, in all these multi-strata systems, a higher density and diversity of shade trees means higher densities and diversity of pollinators and biological pest control agents such as ants and social wasps, which in turn increase cacao yields even more (Bisseleua et al., 2017).

    In conclusion, better land management practices, such as allowing a diversity of shade trees to grow among the cacao crop, increases both biodiversity and revenue for farmers. Tropical agroforestry is thus a promising approach to reconcile biodiversity conservation and economic development. Educating farmers on shaded agroforestry systems and creating complimentary economic incentives and policies would help farmers adapt to better management practices faster, ultimately allowing agroforestry systems to contribute more to biodiversity conservation. A guilt-free sweet tooth, indeed!

    Figure 18.2.4 (Top) Cacao grown as a monoculture, without shade trees, in Ghana. Biodiversity is greatly reduced and the cacao trees are more susceptible to pests and diseases in this framework. Photograph by Phillip Allman, CC BY 4.0. (Bottom) Coffee grown under a diverse canopy of trees in Ethiopia. Like cacao, coffee cultivated under shade provides a forest structure in which birds, insects, and other wildlife can flourish. Photograph by Evan Buechley, CC BY 4.0.

    Improved logging practices

    Conservationists are also dependent on extractive industries. Rather than criticize, it is more productive to partner with and influence these industries to contribute to conservation efforts.

    As with intensive agriculture, high-impact resource extraction industries have not traditionally been compatible with conservation needs. These include mining, oil and gas extraction, dredging, quarrying, and logging, which have often been associated with complete ecosystem destruction. While it is easy to criticize these industries for their impact on nature, it is important for conservationists to remember that we are all dependent on those industries in some way or other, even to perform our conservation activities. Rather than criticize, it is more productive to partner with and influence with industries to contribute to conservation efforts.

    There are many examples illustrating how partnerships between conservation biologists and extractive industries can benefit conservation. One of the best examples comes from the timber industry, which has the potential to greatly increase forest conservation opportunities (Clark et al., 2009). Traditionally known for leaving unsightly clear-cuts behind them, research has shown that improved logging techniques facilitate quicker ecosystem recovery after harvesting, which in turn also benefits biodiversity. For example, while the response of wildlife to logging differs depending on the harvesting method and forest type (Ofori-Boateng et al., 2013), primates (Stokes et al., 2010; Morgan et al., 2018), amphibians (Ofori-Boateng et al. 2013), and birds (Şekercioğlu, 2002) can all tolerate responsible-done light-touch logging techniques (but see also Bicknell et al., 2013; Gatti et al., 2015).

    Guided by this research, some sectors of the timber industry have been keen to adopt more sustainable logging techniques (Figure 18.2.5) that focus on reducing damage to the soil, stream banks, and remaining trees, while removing just the largest trees. This approach reduces soil disturbance, erosion, waste, and carbon emissions. The Forest Stewardship Council (FSC) and other similar organizations are setting certification standards for sustainable logging, which enable certified logging operations to sell their products at higher prices on world markets. In addition to impact reduction within logged areas, certification schemes typically also require timber companies to avoid logging high conservation value forests, which is a good strategy for protecting ecosystem services and biodiversity in general. Some agroforestry companies also allow local people to cultivate rare medicinal and aromatic plants in the shaded areas on their concessions which reduces harvesting pressure on wild populations (Rao et al., 2004). Lastly, a key element for wildlife management in logged forests is to stop hunters, fishers, trappers, and plant collectors from entering the impacted area after timber harvest by closing unused logging roads. (For more discussion on the impact of the logging road on biodiversity, see Laurance et al., 2014 and Benítez-López et al., 2017.)

    Figure 18.2.5 Reduced impact logging techniques facilitate quicker ecosystem recovery. In this example from Mozambique, foresters took only the largest trees, and left some scattered logging slash (i.e. cut branches) to provide shelter for wildlife and to promote natural seed germination. Logged areas are also surrounded by stands of intact forest to promote wildlife and seed dispersal. Photograph by Johnny Wilson, CC BY 4.0.

    This page titled 18.2: Human-Dominated Landscapes is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by John W. Wilson & Richard B. Primack (Open Book Publishers) via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.